Audio Blackbox: Past Recorder

Audio Blackbox keeps the last minutes of sound in your phone's memory, so you can save something after it happened. Played a riff you want to keep? Said an idea out loud? Agreed on something in a meeting you were part of? Tap Save and those minutes become an audio file.

Nothing is written to storage until you tap Save, and the app has no internet permission, so it never uploads your audio anywhere.

Made for
• Musicians and songwriters: keep the riff or melody you just played, without having pressed record first.
• Ideas and thinking out loud: save the thought before it slips away.
• Meetings and agreements you are part of: keep what was just agreed.
• Family moments: the first word, the funny line, the song at the dinner table.

How it works
• Turn on continuous recording. A visible notification stays up the whole time the app is recording.
• Audio goes into a rolling buffer in RAM. When the buffer is full, the oldest audio is replaced by the newest.
• The buffer is at least 5 minutes, set in 5-minute steps. There is no fixed maximum: the app works out how much your phone can safely hold for the quality preset you picked, and shows that limit in Settings.
• Save writes the buffered audio since your last save (the whole buffer the first time) to an AAC (.m4a) file, so your files never overlap.
• Live starts a recording that keeps the buffered past and continues until you stop it.

Features
• Three quality presets: Voice (16 kHz mono, the longest buffer), Balanced (32 kHz mono) and High fidelity (44.1 kHz stereo, which can use more than one microphone on phones that have them). Higher quality uses more memory per minute, so the buffer gets shorter.
• Home-screen widget to start or stop recording with one tap.
• Save, Live and Stop right from the notification.
• Pauses when another app takes the microphone, such as a phone call, and resumes on its own once it is free.
• Built-in player to listen, seek, share and delete your saved recordings.

Privacy
• No internet permission in the app. No account, no ads, no analytics, no cloud.
• Audio stays in memory until you save it. The app never uploads anything: saved files go to your phone's Recordings/Blackbox folder (Music/Blackbox on Android 10 and 11), where you control them.
• Free and open source under GPL-3.0, actively maintained, with the full source code on GitHub.

Record responsibly
Use Audio Blackbox for your own conversations and ideas. Recording other people may require their consent, and the rules differ between countries and states. Check your local recording laws before you record. You are responsible for how you use the app.